Guitar construction

ABSTRACT

A guitar includes a body comprised of a one-piece curved bowl of fiberglass material forming the back and sides of the body and a flat wooden soundboard forming the top of the body. A unique arrangement of braces secured to the interior surface of the soundboard causes it to be tuned to a large number of different frequencies over the fully frequency and produces a full rich sound when the instrument is played.

United States Patent [151 3,656,395 Kaman 1451 Apr. 18,1972

1541 GUITAR CONSTRUCTION 1,889,408 11/1932 Larson ..84/267X I 2,204,1506/1940 Quattrociocche... 84/267 [72] Invent 3,443,465 5/1969 Kasha.,..84/267 [73] Assignee: Kaman Corporation, Bloomfield, Conn. 3,515,0246/1970 Broussard ..84/291 221 Filed: June 8, 1970 U.S. C1 ..84/267,84/291 Int. Cl ..G10d l/08, G10d 3/00 Field of Search ..84/267, 268,274, 275 291, 84/294- References Cited UNITED STATES PATENTS 1,179,4994/1916 Bohmann.... ..84/267 3,474,697 10/ 1969 Kaman ..84/267 1,764,6796/1930 Gast ..84/267 X App]. No.: 44,202

Primary ExaminerRichard B. Wilkinson Assistant Examiner-John F. GonzalesAttorney-McCormick, Paulding and Huber [5 7] ABSTRACT A guitar includesa body comprised of a one-piece curved bowl of fiberglass materialforming the back and sides of the body and a flat wooden soundboardforming the top of the body. A unique arrangement of braces secured tothe interior surface of the soundboard causes it to be tuned to a largenumber of different frequencies over the fully frequency and produces afull rich sound when the instrument is played.

22 Claims, 28 Drawing Figures PATENTEDAPR 18 1972 INVENTOR. CHARLES H.KAMAN ATTORNEYS I PATENTEDAP 18 I372 sum NF 5 1 GUITAR CONSTRUCTIONBACKGROUND OF THE'INVENTION This invention relates to guitars, and dealsmore particularly with a guitar construction for producing an improvedcharacter of sound from the instrument.

The guitar construction of this invention is intended primarily for usein acoustic guitars, and is shown and described herein in connectionwith such guitars. However, the scope of the invention is notnecessarily so limited and where applicable it may, if desired, also beapplied to electric guitars. In any guitar, the fundamental source ofsound is a vibrating string or strings. These vibrating strings,however, by themselves emit only very low levels of sound, and to renderthe sound acceptably audible, it'is necessary to amplify it, or moreprecisely to increase the coupling between the vibrations and thesurrounding air. In an acoustic guitar this amplification is achieved bytransmitting the vibrations of the strings through a bridge to the topof the instrument body, referred to herein as the soundboard and formingpart of a soundboard assembly including in addition to the soundboard aplurality of interior braces which modify the acoustic response of thesoundboard. Of course, when a particular musical note is played byplucking a string the tone produced consists not only of the fundamentalfrequency of the note but also various overtones or harmonics of suchnote, and the degree to which the note is amplified by the soundboardassembly, as well as its tonal character or timbre, will depend on theresponse of the soundboard assembly to the fundamental frequency and toits various harmonic frequencies.

In previous guitar constructions, the soundboard assembly tends toemphasize certain frequencies and to de-emphasize other frequenciesoverv the audible range. This is due to the soundboard assembly havingthe characteristic of being resonant to certain frequencies, which areemphasized, and substantially non-resonant to other frequencies, whichare not emphasized. The result is that if the frequency responsecharacteristic (frequency vs. volume of emitted sound for a fixedexcitation) of the soundboard assembly is plotted the 'response curvewill be found to have several spaced peaks representing frequencies thatare emphasized and alternating with spaced valleys representingfrequencies which are not emphasized. When a guitar with such asoundboard assembly is played, particularly in loud chords, the soundtends to break-up and to become unpleasing to the ear. This is becausethe energy of the emitted sound is concentrated-at the few resonantfrequencies of the soundboard assembly and as the chordal structurebecomes more complex and the vibrationsof the strings become moreintense the contrast between these resonant frequencies and thefrequencies becomes more material so as to produce a more unpleasantsound.

To produce a fuller and richer tone, and to overcome the tendency of thesound to break-up when the instrument is played in loud chords, thesoundboard assembly of this invention is constructed so as to beresonant or tuned to a large number of different frequencies over theaudible range of frequencies, thereby producing a smoother responsecurve having less contrast between its peaks and valleys and tending toemphasize practically all frequencies to a considerable extent. Inparticular, the soundboard assembly of a guitar made in accordance withthis invention includes braces on its interior surface so arranged as tocause the soundboard to have a number of different resonant areas foreach particular frequency of the audible range. That is, for aparticular fundamental frequency, the soundboard has distributed overits surface a number of different small areas which tend to vibrate in asubstantially resonant fashion in response to such frequency. At anotherfundamental frequency, the soundboard includes a number of otherdifferently located areas which tend to frequency of the fundamentaltone changes, but as a general rule for any given excitation frequencythe soundboard surface. includes at least some area which responds in agenerally resonant manner to amplify such frequency. Accordingly,although the response curve may include some peaks at frequencies whichare emphasized somewhat more than others, the response between such peakproducing frequencies is more filled in and contains less deep valleysor low response frequencies than heretofore. In addition to this givingthe guitar a morepleasant tone, it also tends to give it more volume,better carrying power and long sustained notes due to the fact that thesoundboard assembly tends to readily resonate at any frequency withsmall excitation of the string or strings.

An addedbenefit of the invention is that the particular bracing employedgreatly improves the sound produced by practically all soundboardmaterials and therefore not only permits one to obtain a highly superiorsound from the better and more expensive grades of soundboard materialsbut to also obtain a very acceptable sound from less expensivesoundboard materials such as plywood.

SUMMARY OF THE INVENTION The present invention resides in a guitarhaving a body with a soundboard assembly including a soundboard, abridge attached to. the exterior surface of the soundboard below thesound opening, and bracing secured to the interior surface of thesoundboard for modifying the frequency response of the soundboard andmore particularly for causing it to resonate and produce a significantresponse at almost any excitation frequency. The bracing consists of amain top brace and a main bottom brace both arranged obliquely to thecenter line of the soundboard, in different directions of inclination,and extending across the bass and treble sides of the soundboard to forma generally V-shaped figure having an apex on the treble side of thesoundboard. The upper or treble-side end of the bottom main brace islocated at approximately the level of the bridge and the lower ortreble-side end of the top main brace may be located directly adjacentthereto or may be spaced some distance upwardly therefrom. The area ofthe soundboard located between the two main braces comprises essentiallya diaphragm in approximately the center of which the bridge is located.The bracing further includes a plurality of fan braces, of smallercross-section than the main braces, having upper ends located adjacentthe'top main brace and extending generally downwardly toward the bottommain brace,

missing or de-emphasized vibrate in a substantially resonant fashion inresponse to such the fan braces being spaced from one anothertransversely of the soundboard and being inclined relative to thesoundboard center line so that each has its upper end located closer tosuch center line than its bottom end. Preferably, an additional brace islocated above the sound opening and is inclined relative to thesoundboard center line in the direction opposite to the inclination ofthe top main brace. Another brace may be applied in some cases to extendgenerally perpendicularly to and across the lower ends of some of thebass-side fan braces. The soundboard is preferably tapered in going fromits top to its bottom so as to be thicker at its top than at its bottom,and on its interior surface the soundboard may be additionally thinnedout in areas located below the bottom main brace and/or above the topmain brace. In addition'to the soundboard assembly, the body of theguitar includes side and back walls and preferably these latter wallsare part of a one-piece back having a rounded back wall curved both inthe longitudinal and transverse directions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view ofa guitar embodying the present invention, part of the lower right-handcorner of the soundboard being broken away to show other details.

FIG. 2 is a side elevational view of the guitar of FIG. 1 with part ofthe bowl of the body being shown broken away to reveal other details.

FIG. 3 is a transverse sectional view taken on the line 3-3 of FIG. 1.

FIG. 4 is a plan view, drawn on a slightly enlarged scale from that ofFIG. 1, showing the interior surface of the soundboard of the FIG. 1guitar and the bracing secured thereto.

FIGS. 4A through 4H are side elevational views of the various braces ofFIG. 4.

FIG. 5 is a plan view generally similar to FIG. 4 but showing bracingarranged slightly differently from that shown in FIG. 4

FIG. 6 is a front elevational view of another guitar embodying thepresent invention.

FIG. 7 is a plan view, drawn on a slightly enlarged scale from that ofFIG. 6, showing the interior surface of the soundboard of the FIG. 6guitar-and the bracing secured thereto.

FIGS. 7A through 71 are side elevational views of the various braces ofFIG. 7.

FIG. 8 is a plan view generally similar to FIG. 7 but showing asoundboard additionally including thinned areas.

FIG. 9 is a sectional view taken on the line 9-9 of FIG. 8.

FIG. 10 is a sectional view taken on the line 10-10 of FIG. 8.

DETAILED DESCRIITION OF THE PREFERRED EMBODIMENTS Referring now to thedrawings, and first particularly to FIGS. 1 to 4, these figuresillustrate one embodiment of a guitar made in accordance with thepresent invention. The guitar is indicated generally at 10 and includesa hollow body or sound box 12 comprised of a one-piece curved bowl 14and a soundboard assembly 16 including a fiat top plate or soundboard18. The bowl 14 is preferably made of a resin impregnated fabric such asplies of fiberglass fabric impregnated with an epoxy resin and laminatedto an appropriate thickness. The bowl has a generally inwardly curvingwaist characteristic of a conventional acoustic guitar. It terminates ina forward edge 20 and, as shown best in FIGS. 2 and 3, has atwo-dimensionally curved rear wall which produces a correspondinglycurved acoustically effective inner surface 22 which tends to reflectsound more clearly and project it farther than a more conventional flatsurface. The side portion of the bowl, which terminates in the forwardedge 20, includes generally U- shaped upper and lower bouts,respectively indicated at 24 and 26, connected by inwardly curvedcentral bouts 28, 28 which form the waist of the instrument. The sideportion of the bowl adjacent the forward edge 20 is substantiallyperpendicular to the soundboard l8, and the soundboard is attachedthereto by an L-shaped strip 30 having one leg bonded to the bowl l4 andits other leg bonded to the soundboard 18, as by adhesive. Included inthe soundboard 18 is a sound opening 32 of circular shape having itscenter located on the longitudinal center line of the soundboardslightly above the level at which the waist of the instrument is of aminimum transverse dimensron.

Also included in the guitar 10 is a neck 34, connected to the body 12,terminating in a peghead 36 and carrying a fret board 38 having aplurality of frets 40, 40. The illustrated peghead 36 accommodates sixstrings 42, 42 which at their lower end are attached to a bridge 44including an upright transversely extending bridge member 45. There arefourteen frets 40, on the illustrated fret board 38 between the peghead36 and the top of the body 12, and this is a characteristic common toso-called folk guitars. Except for the soundboard assembly 16, which ishereinafter described in more detail, the guitar 10 is or may beidentical to the one shown in US. Pat. No. 3,474,697 to which referencemay be had for further details of its construction. I

The soundboard assembly 16 includes the soundboard 18, the bridge 44 anda unique arrangement of bracing secured to the interior surface 46 ofthe soundboard. It may also include, on the exterior surface 50 of thesoundboard, a rosette or purfling ring 48 surrounding the sound opening32 and possibly a band of purfling or other edge trim extending alongthe outer edgev of the soundboard, but these details do not form anypart of the present invention.

The soundboard 18 is preferably made of a single thickness of wood, suchas spruce, and also, as shown best in FIG. 2, is preferably tapered fromtop to bottom so as to have a greater thickness at its top than at itsbottom. This provides the body 12 with maximum strength at its upper endwhere it is attached to the neck 34 while providing the soundboard withgreater freedom of vibration in its lower region. It should be noted,however, that this tapering is not absolutely necessary to the broaderaspects of the invention and if desired the soundboard may be made witha uniform thickness from top to bottom. In fact, one of the benefits ofthis invention is that the bracing applied to the interior surface ofthe soundboard enables what were previously considered to be poorsoundboard materials to produce greatly improved tonal results; and byusing the present invention very good sounding guitars may be made usinguntapered soundboards of relatively low cost material such as plywood.

The present invention involves primarily the arrangement of the bracingapplied to the interior surface of the soundboard of a guitar. Beforeconsidering in detail the particular bracing applied to the guitar 10 ofFIGS. 1 to 4, it should be understood that the arrangement ofthe bracingmay vary slightly from one instrument to another, without departing fromthe invention, in order to best suit other design parameters of theguitar and/or to produce a desired tonal effect such as increase ordecrease in the bass or treble response. As to the other designparameters, the more important ones involve the style of the guitar, itsnumber and type of strings and the size of its body. conventionally,acoustic guitars are made in either a folk style or a classic style, andthe strings may be either metallic or non-metallic. Also, the size ofthe body and consequently its volume and the size of its soundboard mayvary slightly from model to model. The folk" style is characterized by along neck having a fret board with fourteen frets between the pegheadand the instrument body, and the classic style is characterized by 'ashorter neck with a fret board having 12 frets between the peghead andthe instrument body. The string lengths are, however, the same for bothstyles with the requirement therefore that the bridge be located loweron the soundboard in the classic style than it is in the folk style.Metal strings are held at a higher tension when tuned than arenonmetallic strings and therefore the bridge in a metal stringed guitarabsorbs a higher string load than does the bridge of a guitar withnon-metallic strings. Also, the bridge of a l2-string guitar obviouslyhas approximately twice the string load applied thereto as does thebridge of a six-string guitar. It is therefore seen that the location ofthe bridge and the string load imposed thereon, as well as the size ofthe soundboard and the volume of its body, may vary from one guitar toanother, and in order to obtain optimum results from such differentguitars it may be necessary to use in them slightly different variationsof the bracing of this invention. By way of example, several differentvariations of the bracing falling within the scope of the invention areillustrated by the various figures presented in this application.

Turning next specifically to FIG. 4 and to FIGS. 4A to 4H, these figuresshow a presently preferred arrangement of bracing for the guitar 10 ofFIG. 1 which is a six-string folk style guitar having a relatively largebowl. In referring to these figures, the bracing includes a number ofindividual braces, 4A to 4H, all of which are bonded to the interiorsurface 46 of the soundboard by adhesive and all of which are made ofwood such as spruce. Also all of the braces, except for the brace 4Epreferably have their end portions tapered by concave scallops 56, 56.The scalloping is provided primarily to produce a thin section on eachbrace end to which it is applied. The manner of achieving this endthinning is not however extremely critical and if desired, particularlywith the fan braces, other shaping of the braces may be used such as agradual feathering as used on the braces 7E to 71 hereinafter discussed.The braces consist of a top main brace 46 and a bottom main brace 4F,both of which are inclinded relative to the longitudinal center-line 52of the soundboard and extend across both the bass and treble side of thesoundboard to form a generally V-shaped figure having an apex on thetreble side. As shown in FIG. 4, the bass side of the soundboard is theright hand side and the treble side the left hand side, the bass sidebeing the side underlying the lower pitched strings 42, 42 and thetreble side being the side underlying the higher pitches strings 42, 42in the completed instrument. All four ends of the top main brace 4G andthe bottom main brace 4F terminate slightly short of the outer edge 54of the soundboard. The top main brace'4G is arranged so that itsbass-side end 58 is located within the vertical region of the soundboarddefined by the center and the lowermost extent of the sound opening. InFIG. 4, the line 60 indicates the level of the center of the soundopening and the line 62 indicates the level of the lowermost extent ofthe sound opening, the region containing the end 58 being the regionbetween the lines 60 and 62. The treble-side end of the top main brace4G is located at a lower level than its bassside end and within thevertical region defined by the lowermost extent of the sound opening anda lower limit located approximately at the level of the bridge. In FIG.4, the approximate level of the bridge is indicated by the line 66 andthe region containing the end 64 is therefore the region between thelines 62 and end 64 in FIG. 4 is, in fact, a spot spaced some distanceabove the level 66 of the bridge.

The bottom main brace 4F is arranged so that its treble-side end 68 islocated at approximately the level of the bridge and with its bass-sideend 70 located a considerable distance therebelow. The location of thetreble-side end 68 of the bottom main brace at approximately the levelof the bridge has been found to be fairly critical and is one standardwhich should be maintained in making slight variations of the bracingfor different guitars.

The top main brace 40 and the bottom main brace 4F are the primarybraces of the invention and, except for the brace 4H, are of relativelylarger cross-section and stiffness than the other braces. Thearrangement of the braces 4I and 4G defines an area of the soundboardlocated therebetween which acts somewhat as a diaphragm and inapproximately the middle of which the bridge resides. As thisdiaphgram-like portion of the soundboard is vibrated by the bridge, themain braces tend to transmit these vibrations to other portions of thesoundboard located above and below such braces to also bring them intovibration.

In addition to the main braces 4G and 4F, the bracing of FIG. 4 alsoincludes five fan braces 4A, 4B, 4C, 4D and 4E.,

The two fan braces 4A and 4B are located on the treble side of thesoundboard and the three braces 4C, 4D and 4E are located on the bassside of the soundboard. All of the fan braces are spaced transversely ofthe soundboard from one another, and they are arranged in a fan fashionso that each is inclined relative to the longitudinal center line 52with its upper end located closer to such center-line than its bottomend. The upper end of each fan brace is located adjacent the top mainbrace 4G and each extends downwardly toward the bottom main brace 4F.The three fan braces 4A, 4B and 4C have their bottom ends locatedadjacent the bottom main brace 70, but the lower ends of the braces 4Dand 4E are spaced laterally outwardly beyond the lower end 70 of thebottom main brace and terminate slightly short of the outer edge 54 ofthe soundboard. The brace 4E is scalloped at only its lower end and atits upper end engages the top main brace and is preferably bonded firmlythereto. The fan braces, 4A to 4E, have a substantial effect on thesound produced by the soundboard and in addition to aiding intransferring vibrations from the diaphragm area to other portions of thesoundboard also appear to have the effect of breaking up the area of thesoundboard into a larger number of potential resonating areas.

It has been found that the tone or sound of the instrument is alsousually improved by placing a brace, such as the one 66. The exactlocation of the shown at 4H, above the sound opening and arranged toextend across a major part of both the bass and treble sides of thesoundboard with its longitudinal axis inclined relative to thesoundboard center line oppositely to the inclination of the top mainbrace 4G so that its bass side end is lower than its treble side end.The brace 4I-I is preferably relatively thick in both itscross-sectional dimensions so as to be relatively stiffer than the fanbraces 4A to 4E.

With regard to the arrangement of the top main brace 46 and the bottommain brace 4F, it has been found that by varying the spacing betweentheir treble-side ends 64 and 68 the tonal response of the instrumentmay be controlled to some extent. In particular, increasing the spacingbetween these ends tends to de-emphasize the bass frequencies, andbringing them closer together tends to emphasize the bass frequencies.The volume of the bowl generally has a similar effect on the response ofthe instrument. That is, a large volume bowl tends to emphasize the bassfrequencies and a smaller volume bowl tends to de-emphasize the bassfrequencies. In the instrument 10 of FIGS. 1 to 4, the body is onehaving a relatively large volume and, therefore, the treble-side ends 64and 68 of the main braces 40 and 4F are spread a substantial distancesince the large volume of the bowl already produces a sufficient bassresponse and no enhancement of it is required. In a smaller volume bowl,however, the ends 64 and 68 of the main braces 4G and 4F may be placedcloser together to obtain a greater bass response to compensate for thesmaller volume of the bowl which normally produces less emphasis of thebass frequencies.

FIG. 5 illustrates a soundboard assembly generally similar to that shownin FIG. 4 but wherein the bracing has been arranged to achieve a greaterbass response, thereby in general rendering it suitable for use on aguitar having a smaller volume body than that of the guitar 10. In FIG.5, the various illustrated parts are substantially identical to those ofFIG. 4 and therefore the same reference numerals have been used as inFIG. 4, except for being primed, and the various parts need not beredescribed in detail. It should be noted in FIG. 5, however, that thebottom main brace 4F is arranged at approximately exactly the samelocation as the bottom main brace 4F of FIG. 4 so that its treble sideend 68' remains at the spproximate level of the bridge. The closing ofthe space between the ends 64' and 68 is accordingly achieved by movingthe end 64 of the top main brace 46 downwardly from the positionoccupied by the corresponding end 64 of FIG. 4. Also, the treble-sideend portions of the main braces 46 and 4F are not scalloped in theconstruction direct contact with one hesive.

Referring next to FIGS. 6, 7 and 7A through 7], these figures relate toa guitar, indicated by the reference numeral 72, which in contrast tothe guitar 10 of FIG. 1 is of a classic style rather than of a folkstyle. That is, it includes a fret board 74 having twelve frets 76, 76between the peghead 78 and the body 80, and consequently its bridge 82is located lower on its soundboard 84 than is the bridge 44 of FIG. 1.Except for this difference and the difference in the bracing applied tothe interior surface of the soundboard 84, the guitar 72 of FIG. 6 isbasically similar to the guitar 10 of FIG. 1 and, except for itsbracing, need not be described in further detail.

FIG. 7 shows the bracing applied to the interior surface 86 of thesoundboard 84 of the guitar 72, and FIGS. 7A through 7.! show the sideelevations of the various individual braces employed. The bracing shownin FIG. 7 includes a top main brace 7B and a bottom main brace 7C. Thetop main brace 7B is located and arranged approximately similarly to thetop main brace 40 of FIG. 4, but the bottom main brace 7C is locatedsomewhat lower than the bottom main brace 4F of FIG. 4 so as toaccommodate the lower location of the bridge and to maintain itstreble-side end 88 at approximately the level of the bridge 82, suchapproximate level being indicated by the line 90.

of FIG. 5 and are brought into another and bonded together by an ad-Between the top main brace 78 and the bottom main brace 7C the bracingof FIG. 7 includes six fan braces, 7D to 71, located in the area betweenthe main braces and spaced transversely from one another relative'to thesoundboard. Each of the fan braces, 7D to 7I, has its upper end locatedadjacent the upper main brace 78 and extends downwardly from such uppermain brace toward the bottom main brace 7C. Three of the fan braces, 7D,7E and 7F, are located on the bass side of the soundboard 84 and thethree other of the fan braces, 76, 7H and 7I, are located on the trebleside of the soundboard. They are collectively arranged in a fan fashionso as to be inclined relative to the center line of the soundboard witheach having its upper end located closer to the center-line than itsbottom end. As shown, each of the fan braces has its upper end taperedby a gradual feathering, except for the one brace 7D which has anuntapered upper end, and all the fan braces are shaped to graduallytaper to a small thickness at their lower ends.

In addition to the two main braces and the fan braces, it has also beenfound to be generally beneficial to add a supplementary bottom brace,such as shown at 7J, to the bracing arrangement of FIG. 7. Thissupplemental bottom brace 71 is located near the lower ends of andarranged generally perpendicular to the bass-side fan braces 7D, 7E and7F, and in the illustrated case extends between and directly contactsthe sides of the bottom main brace 7C and the outermost bass-side fanbrace 7D. It has still further been found that usually an improved soundmay be produced with the above described bracing of FIG. 7 by alsoincluding in the soundboard assembly an upper supplemental brace,indicated at 7A and generally similar to the brace 4I-I of FIG. 4,located above the sound opening 90 of the soundboard and arranged toextend between the bass side and the treble side of the soundboard withits bass side end lower than its treble side end.

As another refinement of the present invention, it has been found that,when desired, increased treble response of the soundboard may usually beobtained by thinning out areas of the interior surface of the soundboardlocated either below the bottom main brace, above the top main brace orboth. Referring to FIGS. 8, 9 and 10, these figures show a soundboardassembly 83 identical to the soundboard assembly 83 of FIG. 7 except forincluding thinned areas in the soundboard for increasing the trebleresponse. In these figures parts which are identical or similar tocorresponding parts of FIG. 7 have been given the same referencenumerals as in FIG. 7, except for being primed, and need not beredescribed. As shown in FIG. 8 the soundboard 84' in its interiorsurface 86 includes a first depression 92 located below the bottom mainbrace 7C and a second depression 94 located between the top main brace7B and the upper supplemental brace 7A. These depressions 92 and 94 maybe made by making the soundboard with initially planar interior andexterior surfaces and then cutting away material from the interiorsurface in the areas 92 and 94 so that the resulting soundboard in theareas 92 and 94 is thinner than it would be if the interior surface weretruly planar.

As previously explained, the accompanying drawings and the foregoingexplanation thereof relate to several specific examples of thisinvention, and it is intended that the bracing may be varied somewhatfrom these examples without departing from the broader aspects of theinvention. In particular, it should be noted that the number andarrangement of braces supplementary to the two main braces, and locatedoutside of the diaphragm-like area of the soundboard defined by the twomain braces, may vary widely. As to these supplemental braces, it hasbeen found in general that increasing their number tends to emphasizethe treble response and to decrease the bass response. Also, if it isdesired to modify the response of the soundboard to a particularfrequency of vibration this can be done by exciting the soundboard atsuch frequency and locating on its surface various nodes and antinodes,nodes being points at which the soundboard has a low or zero amplitudeof vibration and anti-nodes being points at which the soundboard has ahigh amplitude of vibration. Then, placing a supplemental brace at anode tends to increase the response of the soundboard to the frequencyin question and placing a supplemental brace at an anti-node has thetendency of reducing the response of the soundboard to the frequency inquestion.

Iclaim:

ll. A guitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, a bottom main brace also arranged obliquely tosaid vertical center-line of said soundboard and extending across saidsoundboard from its bass side to its treble side, the treble-side end ofsaid bottom main brace being located at approximately the level of saidbridge and the bass-side end of said bottom main brace being located ata level considerably below that of said bridge, and a plurality of otherbraces extending generally longitudinally of said soundboard and spacedfrom one another transversely of said soundboard, said other bracesbeing located between said top main brace and said bottom main brace.

2. A guitar as defined in claim 1 further characterized by saidsoundboard being tapered from a first thickness at its top to a smallerthickness at its bottom.

3. A guitar as defined in claim 1 further characterized by said body inaddition to said soundboard including means defining side and rear wallsfor said body, said rear wall of said body being curved in twodimensions to provide a correspondingly curved sound reflecting surfacein the interior of said body spaced rearwardly from said soundboard.

4. A guitar as defined in claim 1 further characterized by said otherbraces each having a transverse cross-sectional size and stiffnesssubstantially less than that of said top main brace and said bottom mainbrace.

5. A guitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, and a bottom main brace also arrangedobliquely to said vertical center line of said soundboard and extendingacross said soundboard from its bass side to its treble-side, thetreble-side end of said bottom main brace being located at approximatelythe level of said bridge and the bass-side end of said bottom main bracebeing located at a level considerably below that of said bridge, thebass-side end of said top main brace being located in the verticalregion of said soundboard defined by the center and said lowermostextent of said sound opening.

6. A guitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, and a bottom main brace also arrangedobliquely to said vertical center line of said soundboard and extendingacross said soundboard from its bass side to its treble side, thetreble-side end of said bottom main brace being located at approximatelythe level of said bridge and the bass-sideend of said bottom main bracebeing located at a level considerably below that of said bridge, saidsoundboard having a depression in its interior surface below said bottommain brace so as to render said soundboard thinner in a givenarea belowsaid bottom main brace than it would be if said interior surface weretruly planar.

7. A guitar having a body with a soundboard assembly, said .soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, and a bottom main brace also arrangedobliquely to said vertical center line of said soundboard and extendingacross said soundboard from its bass side to its treble side, thetreble-side end of said bottom main brace being located at approximatelythe level of said bridge and the bass-side end of said bottom main bracebeing located at a level considerably below that of said bridge, saidsoundboard having a depression in its interior surface above said topmain brace so as to render said soundboard thinner in a given area abovesaid top main brace than it would be if said interior surface were trulyplanar.

8. A guitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, a bottom main brace also arranged obliquely tosaid vertical center line of said soundboard and extending across saidsoundboard from its bass side to its treble side, the treble-side end ofsaid bottom main brace being located at approximately the level of saidbridge and the bass-side end of said bottom main brace being located ata level considerably below that of said bridge, and a plurality of fanbraces spaced relative to one another transversely of said soundboardand located between said top main brace and said bottom main brace, eachof said fan braces having an upper end located adjacent said top mainbrace and extending generally downwardly relative to said soundboardfrom said top main brace.

9. A guitar as defined in claim 8 further characterized by saidsoundboard assembly including at least one additional bracesupplementary to said two main braces and said fan braces, said at leastone supplementary brace being disposed outside of that area of saidsoundboard located between said two main braces.

10. A guitar as defined in claim 9 further characterized by said atleast one additional brace being a supplemental brace located above saidsound opening and extending across a substantial portion'of both saidbass side and said treble side of said soundboard.

11. A guitar as defined in claim 10 further characterized by saidsupplemental brace being inclinded relative to said center line of saidsoundboard in such a direction that its bass side end is lower than itstreble side end.

12. A guitar as defined in claim 8 further characterized by said fanbraces including a first plurality thereof located on said bass side ofsaid soundboard and a second plurality thereof located on said trebleside of said soundboard, each of said fan braces of said first pluralitybeing inclined in one direction relative to said vertical center line ofsaid soundboard andeach of said fan braces of said second pluralitybeing inclined in the opposite direction so that each of said fan braceshas its upper end located closer to said center line than its lower end.

13. A guitar as defined in claim 12 further characterized by said fanbraces being so arranged that those located closer to said center lineof said soundboard are inclined at smaller angles to said center-linethan those which are located further from said center-line.

14. A guitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, and a bottom main brace also arrangedobliquely to said vertical center line of said soundboard and extendingacross said soundboard from its bass side to its treble side, thetreble-side end of said bottom main brace being located at approximatelythe level of said bridge and the bass-side end of said bottom main bracebeing located at a level considerably below that of said bridge, saidtop main brace having'its treble-side end spaced above the treble-sideend of said bottom main brace.

15. A guitar as defined in claim 14 further characterized by saidsoundboard assembly including a plurality of fan braces spaced relativeto one another transversely of said soundboard and located between saidtop main brace and said bottom main brace, each of said fan braceshaving an upper end located adjacent said top main brace and extendinggenerally downwardly relative to said soundboard from said top mainbrace.

16. A guitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, a bottom main brace also arranged obliquely tosaid vertical center line of said soundboard and extending across saidsoundboard from its bass side to its treble side, the treble-side end ofsaid bottom main brace being located at approximately the level of saidbridge and the bass-side end of said bottom main brace being located ata level considerably below that of said bridge, said top main bracehaving its treble-side end in engagement with the treble-side end ofsaid bottom main brace, and a plurality of fan braces spaced from oneanother transversely of said soundboard and located between said topmain brace and said bottom main brace, each of said fan braces having anupper end located adjacent said top main brace and extending generallydownwardly relative to said soundboard from said top main brace.

17. A guitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending across.said soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, a bottom main brace also arranged obliquely tosaid vertical center-line of said soundboard and extending across saidsoundboard from its bass side to its treble side, the treble-side end ofsaid bottom main brace being located at approximately the level of saidbridge and the bass-side end of said bottom main brace being located ata level considerably below that of said bridge, and a plurality of fanbraces spaced relative to one another transversely of said soundboardand located between said top main brace and said bottom main brace, saidfan braces consisting of two fan braces located on said treble side ofsaid soundboard and three fan braces located on said bass side of saidsoundboard, the two of said treble-side fan braces and the one of saidbass-side fan braces which is closest to said center line of saidsoundboard extending substantially the entire distance from said topmain brace to said bottom main brace so that their upper ends arelocated adjacent said top main brace and their lower ends are locatedadjacent said bottom main brace, the other two of said bass-side fanbraces having their lower ends spaced laterally farther from saidcenterline than the bass-side end of said bottom main brace.

18. A guitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the

treble-side end of said top main brace being located at a lower levelthan its bass-side end and within the vertical region defined by thelowermost extent of said sound opening and a lower limit locatedapproximately at the level of said bridge, a bottom main brace alsoarranged obliquely to said vertical center line of said soundboard andextending across said soundboard from its bass side to its treble side,the treble-side end of said bottom main brace being located atapproximately the level of said bridge and the bass-side end of saidbottom main brace being located at a level considerably below that ofsaid bridge, and a plurality of fan braces spaced relative to oneanother transversely of said soundboard and located between said topmain brace and said bottom main brace, said fan braces consisting ofthree fan braces located on said treble side of said soundboard andthree fan braces located on said bass side of said soundboard, the threeof said treble-side fan braces and the one of said bass-side fan braceswhich is closest to said center-line of said soundboard extendingsubstantially the entire distance from said top main brace to saidbottom main brace so that their upper ends are located adjacent said topmain brace and their lower ends are located-adjacent said bottom mainbrace, the other two of said bass-side fan braces having their lowerends spaced laterally farther from said center-line than the bass-sideend of said bottom main brace.

19 A guitar as defined in claim 18 further characterized by saidsoundboard assembly including a supplementary bottom brace arrangedgenerally perpendicular 0 said bass-side fan braces and .located nearthe lower ends of said bass-side fan braces.

20. A guitar as defined in claim 19 further characterized by saidsupplementary bottom brace being arranged to directly engage and extendbetween said bottom main brace and the laterally outermost one of saidthree bass-side fan braces.

21. A guitar as defined in claim 18 further characterized by saidsoundboard assembly including an upper supplementary brace locatedgenerally above said sound opening and extending between the bass sideand the treble side of said soundboard;

22. A guitar as defined in claim 21 further characterized by saidsoundboard having a first depression in its interior surface below saidbottom main brace and a second depression in its interior surfacebetween said top main brace and said upper supplementary brace so as torender said soundboard thinner in a given area below said bottom mainbrace and in another given area between said upper main brace and saidupper supplementary brace than it would be if said interior surface weretruly planar.

1. A guitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, a bottom main brace also arranged obliquely tosaid vertical center-line of said soundboard and extending across saidsoundboard from its bass side to its treble sIde, the treble-side end ofsaid bottom main brace being located at approximately the level of saidbridge and the bass-side end of said bottom main brace being located ata level considerably below that of said bridge, and a plurality of otherbraces extending generally longitudinally of said soundboard and spacedfrom one another transversely of said soundboard, said other bracesbeing located between said top main brace and said bottom main brace. 2.A guitar as defined in claim 1 further characterized by said soundboardbeing tapered from a first thickness at its top to a smaller thicknessat its bottom.
 3. A guitar as defined in claim 1 further characterizedby said body in addition to said soundboard including means definingside and rear walls for said body, said rear wall of said body beingcurved in two dimensions to provide a correspondingly curved soundreflecting surface in the interior of said body spaced rearwardly fromsaid soundboard.
 4. A guitar as defined in claim 1 further characterizedby said other braces each having a transverse cross-sectional size andstiffness substantially less than that of said top main brace and saidbottom main brace.
 5. A guitar having a body with a soundboard assembly,said soundboard assembly including a soundboard with generally planarinterior and exterior surfaces and a sound opening passing therethrough,a bridge attached to said exterior surface of said soundboard below saidsound opening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, and a bottom main brace also arrangedobliquely to said vertical center line of said soundboard and extendingacross said soundboard from its bass side to its treble-side, thetreble-side end of said bottom main brace being located at approximatelythe level of said bridge and the bass-side end of said bottom main bracebeing located at a level considerably below that of said bridge, thebass-side end of said top main brace being located in the verticalregion of said soundboard defined by the center and said lowermostextent of said sound opening.
 6. A guitar having a body with asoundboard assembly, said soundboard assembly including a soundboardwith generally planar interior and exterior surfaces and a sound openingpassing therethrough, a bridge attached to said exterior surface of saidsoundboard below said sound opening, and bracing secured to saidinterior surface of said soundboard, said bracing including a top mainbrace arranged obliquely to the longitudinal center line of saidsoundboard and extending across said soundboard from its bass side toits treble side, the treble-side end of said top main brace beinglocated at a lower level than its bass-side end and within the verticalregion defined by the lowermost extent of said sound opening and a lowerlimit located approximately at the level of said bridge, and a bottommain brace also arranged obliquely to said vertical center line of saidsoundboard and extending across said soundboard from its bass side toits treble side, the treble-side end of said bottom main brace beinglocated at approximately the level of said bridge and the bass-side endof said bottom main brace being located at a level considerably belowthat of said bridge, said soundboard having a depression in its interiorsurface below said bottom main brace so as to render said soundboardthinner in a given area below said bottom main brace than it would be ifsaid interior surface were truly planar.
 7. A guitar having a body witha soundboard assembly, said soundboard assembly including a soundboArdwith generally planar interior and exterior surfaces and a sound openingpassing therethrough, a bridge attached to said exterior surface of saidsoundboard below said sound opening, and bracing secured to saidinterior surface of said soundboard, said bracing including a top mainbrace arranged obliquely to the longitudinal center line of saidsoundboard and extending across said soundboard from its bass side toits treble side, the treble-side end of said top main brace beinglocated at a lower level than its bass-side end and within the verticalregion defined by the lowermost extent of said sound opening and a lowerlimit located approximately at the level of said bridge, and a bottommain brace also arranged obliquely to said vertical center line of saidsoundboard and extending across said soundboard from its bass-side toits treble side, the treble-side end of said bottom main brace beinglocated at approximately the level of said bridge and the bass-side endof said bottom main brace being located at a level considerably belowthat of said bridge, said soundboard having a depression in its interiorsurface above said top main brace so as to render said soundboardthinner in a given area above said top main brace than it would be ifsaid interior surface were truly planar.
 8. A guitar having a body witha soundboard assembly, said soundboard assembly including a soundboardwith generally planar interior and exterior surfaces and a sound openingpassing therethrough, a bridge attached to said exterior surface of saidsoundboard below said sound opening, and bracing secured to saidinterior surface of said soundboard, said bracing including a top mainbrace arranged obliquely to the longitudinal center line of saidsoundboard and extending across said soundboard from its bass side toits treble side, the treble-side end of said top main brace beinglocated at a lower level than its bass-side end and within the verticalregion defined by the lowermost extent of said sound opening and a lowerlimit located approximately at the level of said bridge, a bottom mainbrace also arranged obliquely to said vertical center line of saidsoundboard and extending across said soundboard from its bass side toits treble side, the treble-side end of said bottom main brace beinglocated at approximately the level of said bridge and the bass-side endof said bottom main brace being located at a level considerably belowthat of said bridge, and a plurality of fan braces spaced relative toone another transversely of said soundboard and located between said topmain brace and said bottom main brace, each of said fan braces having anupper end located adjacent said top main brace and extending generallydownwardly relative to said soundboard from said top main brace.
 9. Aguitar as defined in claim 8 further characterized by said soundboardassembly including at least one additional brace supplementary to saidtwo main braces and said fan braces, said at least one supplementarybrace being disposed outside of that area of said soundboard locatedbetween said two main braces.
 10. A guitar as defined in claim 9 furthercharacterized by said at least one additional brace being a supplementalbrace located above said sound opening and extending across asubstantial portion of both said bass side and said treble side of saidsoundboard.
 11. A guitar as defined in claim 10 further characterized bysaid supplemental brace being inclinded relative to said center line ofsaid soundboard in such a direction that its bass side end is lower thanits treble side end.
 12. A guitar as defined in claim 8 furthercharacterized by said fan braces including a first plurality thereoflocated on said bass side of said soundboard and a second pluralitythereof located on said treble side of said soundboard, each of said fanbraces of said first plurality being inclined in one direction relativeto said vertical center line of said soundboard and each of said fanbraces of said second plurality being inclined in the opposite directionso that each of said fan braces has its upper end located closer to saidcenter line than its lower end.
 13. A guitar as defined in claim 12further characterized by said fan braces being so arranged that thoselocated closer to said center line of said soundboard are inclined atsmaller angles to said center-line than those which are located furtherfrom said center-line.
 14. A guitar having a body with a soundboardassembly, said soundboard assembly including a soundboard with generallyplanar interior and exterior surfaces and a sound opening passingtherethrough, a bridge attached to said exterior surface of saidsoundboard below said sound opening, and bracing secured to saidinterior surface of said soundboard, said bracing including a top mainbrace arranged obliquely to the longitudinal center line of saidsoundboard and extending across said soundboard from its bass side toits treble side, the treble-side end of said top main brace beinglocated at a lower level than its bass-side end and within the verticalregion defined by the lowermost extent of said sound opening and a lowerlimit located approximately at the level of said bridge, and a bottommain brace also arranged obliquely to said vertical center line of saidsoundboard and extending across said soundboard from its bass side toits treble side, the treble-side end of said bottom main brace beinglocated at approximately the level of said bridge and the bass-side endof said bottom main brace being located at a level considerably belowthat of said bridge, said top main brace having its treble-side endspaced above the treble-side end of said bottom main brace.
 15. A guitaras defined in claim 14 further characterized by said soundboard assemblyincluding a plurality of fan braces spaced relative to one anothertransversely of said soundboard and located between said top main braceand said bottom main brace, each of said fan braces having an upper endlocated adjacent said top main brace and extending generally downwardlyrelative to said soundboard from said top main brace.
 16. A guitarhaving a body with a soundboard assembly, said soundboard assemblyincluding a soundboard with generally planar interior and exteriorsurfaces and a sound opening passing therethrough, a bridge attached tosaid exterior surface of said soundboard below said sound opening, andbracing secured to said interior surface of said soundboard, saidbracing including a top main brace arranged obliquely to thelongitudinal center line of said soundboard and extending across saidsoundboard from its bass side to its treble side, the treble-side end ofsaid top main brace being located at a lower level than its bass-sideend and within the vertical region defined by the lowermost extent ofsaid sound opening and a lower limit located approximately at the levelof said bridge, a bottom main brace also arranged obliquely to saidvertical center line of said soundboard and extending across saidsoundboard from its bass side to its treble side, the treble-side end ofsaid bottom main brace being located at approximately the level of saidbridge and the bass-side end of said bottom main brace being located ata level considerably below that of said bridge, said top main bracehaving its treble-side end in engagement with the treble-side end ofsaid bottom main brace, and a plurality of fan braces spaced from oneanother transversely of said soundboard and located between said topmain brace and said bottom main brace, each of said fan braces having anupper end located adjacent said top main brace and extending generallydownwardly relative to said soundboard from said top main brace.
 17. Aguitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing securEd to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, a bottom main brace also arranged obliquely tosaid vertical center-line of said soundboard and extending across saidsoundboard from its bass side to its treble side, the treble-side end ofsaid bottom main brace being located at approximately the level of saidbridge and the bass-side end of said bottom main brace being located ata level considerably below that of said bridge, and a plurality of fanbraces spaced relative to one another transversely of said soundboardand located between said top main brace and said bottom main brace, saidfan braces consisting of two fan braces located on said treble side ofsaid soundboard and three fan braces located on said bass side of saidsoundboard, the two of said treble-side fan braces and the one of saidbass-side fan braces which is closest to said center line of saidsoundboard extending substantially the entire distance from said topmain brace to said bottom main brace so that their upper ends arelocated adjacent said top main brace and their lower ends are locatedadjacent said bottom main brace, the other two of said bass-side fanbraces having their lower ends spaced laterally farther from saidcenter-line than the bass-side end of said bottom main brace.
 18. Aguitar having a body with a soundboard assembly, said soundboardassembly including a soundboard with generally planar interior andexterior surfaces and a sound opening passing therethrough, a bridgeattached to said exterior surface of said soundboard below said soundopening, and bracing secured to said interior surface of saidsoundboard, said bracing including a top main brace arranged obliquelyto the longitudinal center line of said soundboard and extending acrosssaid soundboard from its bass side to its treble side, the treble-sideend of said top main brace being located at a lower level than itsbass-side end and within the vertical region defined by the lowermostextent of said sound opening and a lower limit located approximately atthe level of said bridge, a bottom main brace also arranged obliquely tosaid vertical center line of said soundboard and extending across saidsoundboard from its bass side to its treble side, the treble-side end ofsaid bottom main brace being located at approximately the level of saidbridge and the bass-side end of said bottom main brace being located ata level considerably below that of said bridge, and a plurality of fanbraces spaced relative to one another transversely of said soundboardand located between said top main brace and said bottom main brace, saidfan braces consisting of three fan braces located on said treble side ofsaid soundboard and three fan braces located on said bass side of saidsoundboard, the three of said treble-side fan braces and the one of saidbass-side fan braces which is closest to said center-line of saidsoundboard extending substantially the entire distance from said topmain brace to said bottom main brace so that their upper ends arelocated adjacent said top main brace and their lower ends are locatedadjacent said bottom main brace, the other two of said bass-side fanbraces having their lower ends spaced laterally farther from saidcenter-line than the bass-side end of said bottom main brace.
 19. Aguitar as defined in claim 18 further characterized by said soundboardassembly including a supplementary bottom brace arranged generallyperpendicular to said bass-side fan braces and located near the lowerends of said bass-side fan braces.
 20. A guitar as defined in claim 19further characteriZed by said supplementary bottom brace being arrangedto directly engage and extend between said bottom main brace and thelaterally outermost one of said three bass-side fan braces.
 21. A guitaras defined in claim 18 further characterized by said soundboard assemblyincluding an upper supplementary brace located generally above saidsound opening and extending between the bass side and the treble side ofsaid soundboard.
 22. A guitar as defined in claim 21 furthercharacterized by said soundboard having a first depression in itsinterior surface below said bottom main brace and a second depression inits interior surface between said top main brace and said uppersupplementary brace so as to render said soundboard thinner in a givenarea below said bottom main brace and in another given area between saidupper main brace and said upper supplementary brace than it would be ifsaid interior surface were truly planar.